My Cloud EX4 - Drive Failure or Enclosure Failure

Got it 👍 — you’re trying to figure out whether the issue with your **WD My Cloud EX4** is due to a **drive failure** or an **enclosure failure**. Let’s go step by step:

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## 1. Symptoms to Check

* **Red LED on one drive bay only** → usually an individual **drive failure**.

* **Multiple drives show errors at once** (especially if they were working fine before) → could be the **enclosure/controller**.

* **System won’t boot at all** (even with drives removed) → likely an **enclosure failure**.

* **Clicking, grinding, or no spin-up from a specific drive** → that’s a **drive failure**.

* **All drives detected but volume not mounting** → enclosure/firmware issue, or RAID metadata corruption.

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## 2. Quick Tests

1. **Remove one drive at a time and test externally**

* Use a SATA-to-USB adapter or connect directly to a PC (Linux reads ext4 RAID partitions better).

* If the drive mounts and files are accessible, the drive is fine.

2. **Swap bays**

* Move a suspected failed drive into another bay.

* If the issue follows the drive → drive problem.

* If the bay itself never detects drives → enclosure/backplane problem.

3. **Test enclosure with known-good drives**

* Insert a clean test drive.

* If enclosure still won’t detect it, the **EX4 enclosure/backplane is failing**.

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## 3. Possible Failure Scenarios

* **Single drive failure in RAID 5/10** → EX4 should still run degraded (but data vulnerable). Replace ASAP.

* **Two drive failures in RAID 5** → volume lost without recovery tools.

* **Controller/firmware corruption** → enclosure won’t present the array even if drives are fine. In this case, you can still read drives in another NAS or with RAID recovery software.

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## 4. Next Steps

* **If it’s a drive failure**: replace with a same-size (or larger) NAS-rated drive, let EX4 rebuild.

* **If it’s an enclosure failure**:

* Try moving drives into another EX4 (same firmware version preferred).

* If not available, connect drives to a Linux PC and assemble RAID manually (`mdadm`).

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👉 Would you like me to guide you through the **drive test method on a PC** (to check each drive’s health), or the **enclosure test** (to see if it’s failing)?